Issue #192: Make it possible to use single letter as commodity name (blais/beancount)

[Zhuoyun Wei]

New issue 192: Make it possible to use single letter as commodity name
https://bitbucket.org/blais/beancount/issues/192/make-it-possible-to-use-single-letter-as

Zhuoyun Wei:

Hi Martin,

this is a similar issue to #138. I recently found out that Beancount currently does not allow single-letter commodity name. A minimal reproducible example:

```
1970-01-01 commodity USD
1970-01-01 commodity V

2017-09-01 open Assets:SingleLetter:X
2017-09-01 open Assets:Trade:Cash USD
2017-09-01 open Assets:Trade:Positions "FIFO"

2017-09-13 * "Buy 10 shares of Visa"
Assets:Trade:Cash -1000.00 USD
Assets:Trade:Positions +10.00 V { 100.00 USD }
```

A bean-check shows:

```
single-letter.beancount:2: Invalid token: 'V'
single-letter.beancount:10: Invalid token: 'V'
```

It seems that single-letter account names do not trigger errors any more (line 4) since #138 is resolved, but single-letter commodity names are still not allowed (line 2 and line 10).

Could you please make single-letter commodity possible? I would like to make pull request but I do not know how to write C code...

Responsible: blais

[Dan Cohen]

Does anyone know a work around?